The invention relates generally to a system and method of stabilizing a patient's beating heart during a medical procedure, such as coronary artery bypass grafting (CABG). More specifically, the invention relates to an apparatus and method for stabilizing the epicardium and occluding the section of the artery to receive a graft vessel.
In a typical CABG procedure on a stopped heart, the patient undergoes a median sternotomy to provide access to the heart area and is put on cardiopulmonary bypass equipment (CPB) to oxygenate the blood and allow the heart to be stopped. These procedures are well known, are safe and are widely accepted for a wide range of medical procedures performed on the heart. A more thorough discussion of a typical CABG procedure can be found in Manual of Cardiac Surgery, Second Edition, by Bradley J. Harlan, MD, Albert Starr, MD and Fredric M. Harwin, BFA, MS, 1995, and a discussion of open heart procedures can be found in Textbook of Interventional Cardiology, Eric J. Topol, 1990, chapters 43-44, pages 831-867, incorporated herein by reference.
It should be understood that while the foregoing CABG procedures are generally regarded as safe and widely accepted, they are not without risks. As is known, when the patient is put on cardiopulmonary bypass equipment, the blood is continuously pumped extracorporeally where it is oxygenated and then returned to the body. Any time the blood is removed from the body there is the risk of infection such as sepsis or other infections that can be serious if not detected and treated. During the oxygenation process, micro-emboli are introduced that are believed to be a major cause of neurological damage which can be temporary or permanent. While the heart and lungs are being bypassed, the heart is infused with cardioplegic fluid to stop the heart from beating and limit damage to the muscle cells due to lack of blood. However, the lungs are not perfused with blood for many hours and this can cause many problems. Also, there is a need to prime the CPB pump with about one liter of fluid. This fluid is pumped into the patient's body in the first few seconds of CPB resulting in a hemodilution of about 20%. As the blood is transported through many feet of tubing and various oxygenators, heat exchangers, and pumps, it is in contact with foreign materials. This contact induces compliment activation which can lead to pulmonary dysfunction, renal dysfunction and further embolic complications. Further, the equipment needed to perform cardiopulmonary bypass is expensive and requires specialized medical personnel to operate and monitor.
During coronary artery bypass procedures using the beating heart approach, the region of the heart which receives the graft vessel must be stabilized so that the graft and suturing procedure can be performed on a substantially stationary epicardium. Presently, this is often performed by threading two sutures through the myocardium with curved needles, on either side of the recipient coronary artery at the site of the anastomosis. The sutures are tensioned to lift the heart and to hold the coronary artery stationary. Suture threads with curved needles swaged on one end are available for this use. Also, suture threads may be used to loop around and tighten the section of artery to be grafted, thereby occluding the artery during the procedure. Again, with the heart beating, placing these suture loops around the artery is difficult due to the movement of the heart and the epicardium surrounding the artery.
Placement of the suture loops may be somewhat difficult, as the heart is beating. The tip of the needle must be placed on the heart, and rotation of the surgeon's wrists must be performed to insert the needle through the myocardium or epicardium. Unpredictable motion of the epicardial surface during needle placement may cause laceration of the heart, puncture of the wall into the ventricle, or puncture of a coronary artery. It is therefore useful to stabilize the anastomotic area during the surgical procedure. There are devices and methods that facilitate the performance of cardiac procedures such as heart valve repair and replacement, coronary artery bypass grafting, and the like, using minimally invasive techniques to eliminate the need for a gross thoracotomy. For example, U.S. Pat. No. 5,425,705 to Evard et al. discloses an apparatus and method for thoracoscopically arresting the heart and establishing cardiopulmonary bypass, thus facilitating a variety of less-invasive surgical procedures on and within the heart and great vessels of the thorax. In one embodiment, Evard provides a thoracoscopic system for arresting a patient's heart including a clamp configured for introduction into the patient's thoracic cavity through a percutaneous intercostal penetration in the patient's chest. The clamp is positionable about the patient's ascending aorta between the coronary arteries and the brachiocephalic artery. The clamp is coupled to the distal end of an elongated handle for manipulating the clamp from a location outside of the patient's thoracic cavity.
It is known to use surgical clips or clamps for the purpose of clamping vessels or manipulating tissue. Typically, such clamps have a pair of movable jaws biased by a spring into a closed position, allowing the clamp to be placed on a vessel or portion of tissue and be firmly retained thereon. Examples of such clamps can be found in U.S. Pat. No. 4,932,955 to Merz et al.; U.S. Pat. No. 4,605,990 to Wilder et al.; U.S. Pat. No. 5,074,870 to Von Zeppelin; U.S. Pat. No. 3,809,094 to Cook; U.S. Pat. No. 4,404,677 to Springer; U.S. Pat. No. 4,051,844 to Chiulli; and U.S. Pat. No. 4,988,355 to Leveen et al.
Outside of the field of cardiac surgery, U.S. Pat. No. 5,415,666 to Gourlay et al. discloses a tethered clamp retractor used for tissue manipulation. The tissue manipulation system includes a tethered clamp, a clamp applicator for positioning the clamp through a trocar sleeve and applying the clamp to a tissue location in the abdominal cavity, and a rigid positioning shaft for engaging the clamp and/or tether to manipulate the clamp.
In view of the shortcomings of the prior art devices, there is a specific need for an apparatus and method for locally stabilizing an anastomotic site during a beating heart coronary artery grafting procedure. What has been needed and heretofore not available is a method of stabilizing the beating heart during a medical procedure without having to perform CPB and subjecting the patient to the attendant risks and complications. The present invention solves the problems of the prior art methods without the resulting risks.